The present invention relates to an intake apparatus of an outboard motor having an improved structure for reducing intake noise.
An outboard motor is generally utilized in a relatively clean environment, and accordingly, an air-intake to an engine unit of the outboard motor is performed by directly taking an atmospheric air (merely, air) without using an air cleaner as an intermediate air cleaning means. Therefore, it is necessary to mount a silencer or like means for reducing noise caused at the air-intake time.
In a conventional usual structure of an outboard motor, a silencer is located in a space defined between an outboard motor cover and an engine body along a side portion of the engine body.
However, in recent years, there is an increasing tendency of utilizing a fuel injection type engine for an outboard motor, and in such type of engine, there is adopted a structure in which an intake manifold, a surge tank and the like means are arranged in the space of the side portion of the engine body, and accordingly, there is less space for the location of the silencer. As a result, only a small-sized silencer can be arranged in this space, which results in an inadequate noise silencing or reducing performance.
Furthermore, in an arrangement in which the air-intake port of the silencer is apart from an atmospheric air intake port provided for the outboard motor cover, the atmospheric air taken into the outboard motor cover is heated by a heat of the engine, and when such heated air is guided into the silencer, there may cause a case of reducing an engine output because of increased intake air temperature.